Music 680: Special Topics in Music Theory - Electronics in Performance (Fall 2006)
Class 3: September 25, 2006
Karlheinz Stockhausen / Mikrophonie I (1964) for tam-tam, electronics, and six performers
overview of the work
a particular kind of interactivity
"dual trios" of percussionist, microphonist, electronics operator
via the shared tam-tam
via the interdependence of the three performance roles
introduction to the notation
verbal explanation, onomatopoeia, and the scale of vowel brightnesses
and the relationship to filtering: formants as an acoustical phenomenon
but also rhythmic, pitch, and gestural precision
introduction to the form
moment-form as a series of self-contained gestures/textures/ideas
variety of possible durations but all internally unified
variable arrangement according to a form-scheme
specifying the general dramatic arc of the piece but not its specific sequence
the "Brussels form" as a worked-out realization (and a standard of performance)
musical structure: moment-form
division into "monadic" and "complex" moments
most moments qualify as monadic
single or a small number of musical elements
typically either static or "punctuated"
contrasting center section, or contrasting / evolving conclusion
generally sounds exist /persist rather than evolve: material rather than process
at least partly due to the nature of the tam-tam as an instrument
even "collage" moment only deals with 2 groups of materials (plus plucking)
complex moments bear substantial responsibility for form
because of distribution in time: periodic insertions with emphasis on back-weighting
often involving reprises of monadic materials (X, Y, TUTTI 157)
intensification and reinterpretation (via reshuffling) of overall collage form
processual in nature: rhythmic and sonic development (cf. gradual changes in Y)
rhythmic/sonic connections between collaged materials (vertical and horizontal)
(cf. TUTTI 157)
as moments of focus / intensification
(TUTTI forte, TUTTI pianissimo)
strangeness (relative to other materials) as a crucial element
in this case achieved through extension in time (both are long duration)
and through coordination: TUTTIs are unusual in direct vertical relationship
issues for realization:
filtering: what quality of filtering?
ergonomics: how to make this viable for the electronics operators?
can the original be improved upon?
electronics functions: amplification, panning, filtering
audio modules and useful techniques
amplification: quartic control
implement using Pd abstractions
inlet, inlet~, outlet, outlet~ objects facilitate creation of custom Pd objects
useful here since every audio function is duplicated for two musicians
panning: constant power
panning front to rear as a curve between 0 and pi/2 radians
front output volume as cos theta
rear output volume as sin theta
[from trigonometric identity: (cos theta)^2 + (sin theta)^2 = 1]
remember that Pd signal~ objects map the unit circle from 0 to 1, not 0 to 2pi!
filtering:
as an application of delay (and flanging)
using constructive/destructive interference to change the spectrum of a signal
typically extremely short delay lengths; can be implemented with/without feedback
FIR filters are feed-forward; require longer delays to achieve a frequency spec
IIR filters use feedback; shorter delays relative to a spec, but can be unstable
"twicing" built-in designs for sharper filters: h[ h[ 3x -2 h [x]]]
user interface
MIDI fader surface
can't have both operators fighting over a single keyboard and mouse
(and indeed might even be preferable to use two separate control surfaces)
dual-fader-in-a-single-channel design of the original electronics
onscreen display: slider objects, font changes, etc.
control logic governing filter parameters
reducing 0-127 MIDI fader ranges to discrete filter steps
allowing "high bound" changes to reduce "low bound"
possibility of automation: mockup of GERAUSCH moment
preview for next week: Babbitt